The one at Cunnagher in County Mayo is a quiet example of a type that has been puzzling archaeologists for generations. A fulacht fia typically takes the form of a low, horseshoe-shaped mound of fire-cracked stone, usually found close to a water source. The prevailing theory holds that these were Bronze Age cooking sites, where stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil, but alternatives have been proposed over the years, including use for bathing, brewing, or textile processing. The cracked and shattered stones, rendered useless by repeated heating and quenching, were simply raked aside after each use, and over centuries that discarded material built up into the distinctive mound shape that survives today.

The site at Cunnagher sits within a landscape that would have been actively settled and worked during the Bronze Age, a period roughly spanning 2500 to 500 BC in Ireland. Mayo has no shortage of prehistoric remains, and fulachtaí fia in the west of Ireland are often found in boggy ground or near streams, the very conditions that tend to preserve organic material and clarify the original relationship between the monument and its water supply. Without more detailed excavation records for this particular site, it is difficult to say more about its precise character or condition, but its presence in the townland of Cunnagher adds one more point to the dense constellation of Bronze Age activity that the Mayo landscape quietly holds.